Heat exchange apparatus



Jan. 22, 1935. w. D. LA MONT HEAT EXCHANGE APPARATUS Filed April 23,1930 WITNESS Q.;f 64

INVENTOR W'qLTER D. LAMONT Patented Jan. 22 1 935 PATENT OFFICE HEATEXCHANGE APPARATUS Walter Douglas La Mont, North Colebrook, Conn.,assignor to La Mont Corporation, New York, N. Y., a corporation of NewYork Application April 23, 1930, Serial No. 446,546

Renewed June 2, 1934- 20 Claims.

This invention relates to heat exchangers, and more particularly tosteam generators of the general type disclosed in my prior ReissuePatent No. 16,895, in which a forced circulation of water is maintainedthrough the generating tubes at a rate in excess of their evaporatingcapacity.

In apparatus constructed to operate in this manner it is essential todistribute the water among the tubes and deliver a sufiicient quantityof water to each individual tube, for if the water supply to aparticular tube should fail, it would almost immediately be damaged bythe heat. In my prior construction I provided an orifice at the entranceend of each tube to control the quantity of water flowing thereto.-These orifices may be .sufliciently large to permit the delivery of thenecessary water under normal conditions, but I have discovered thatthere is serious danger of the orifices becoming obstructed duringoperation by foreign material, such as pipe scale, in the water. Thishas either caused damage to certain of the steam generating tubes ornecessitated the shutting down of the entire steam generator to permitthe removal of the foreignmaterial. Many prior attempts have been madeto overcome this difiiculty,. but none have proven satisfactory so faras I am aware.

It is accordingly the main object of my invention to provide a steamgenerator having orifices at the entrance ends of the steam generatingtubes, in which means is provided to effectively protect the orificesagainst pluggin by foreign material and to ensure an adequate supply ofwaterfor each tube at all times. i

It is a further object of my invention to provide an individual screenfor each orifice of a steam generator, the construction being soarranged that the screens may be easily and effectively cleaned withoutshutting down the generator.

A further object is to provide means for reversing the direction of flowthrough the individual orifice screens and thereby remove any. foreignmaterial collected thereon.

A further object is to provide means to prevent 45 foreign material inthe generating tubes from plugging the orifices when the direction offlow is reversed.

A further object is to provide an individual screened nozzle which isarranged'to be mounted so at the entrance end of a steam generating tubeto supply water thereto, and which is free from danger of clog ing. IWith these and other objects in view, as will be apparent to thoseskilled in the art, my invention 55 resides in the combination of partsset forth in the specification and covered by the claims appendedhereto.

In accordance with.one embodiment of my.

invention I provide a steam generator'having steam generating tubes towhich water is delivered by a suitable forcing means, such as a pump. Aflow restricting orifice is located at the entrance end of each tube,and each orifice is protected by an individual screen mounted close tothe orifice and on the inlet side thereof. Each screen is preferablyshaped as a hollow cylindrical sleeve of non-corrosive metal havingperforacharge side thereof to prevent scale from reaching the orificeduring this cleaning operation.

Referring to the drawing illustrating one embodiment of the invention,and in which like reference numerals indicate like parts,

. Fig. 1 is a vertical sectional elevation of a steam generator;

Fig. 2 is an enlarged cross section through the inlet header, thesection being taken onthe line 2-2 of Fig. 1;

Fig. 3 is a perspective view of the orifice member;

Fig. 4 is a perspective view of the screen for the discharge side of theorifice; and

Fig. 5 is a perspective view'of the sleeve which change apparatus. Theembodiment illustrated I comprises a furnace chamber 10 which ismaintained at a high temperature by any suitable means. For this purposeI have shown an oil burner 11 arranged to deliver oil for combustion inthe furnace in a well known manner.

A boiler 12 of any desired type is mounted above the furnace to absorbheat therefrom by radiation and convection. For simplicity of ii- Ilustration, this boiler 12 has been shown as a horizontal cylindricaldrum forming a receptacle for steam and water under pressure. Water maybe supplied to the drum 12 from any suitable source through a feed pipe14, and steam may be withdrawn from the drum through a pipe 15 leadingto a main steam header 16.

Adjacent to one wall of the furnace chamber 10 I have shown a water wallcomprising spaced parallel horizontal tubes 18 arranged to generatesteam by the absorption of radiant heat from the furnace and to protectthe refractory material of the wall behind them. The tubes 18 areconnected at one end to a vertical pipe or inlet header 19, and at theiropposite ends to a vertical outlet header 20. A suitable forcing means,such as a centrifugal pump 22 driven by an electric motor 23, isprovided to circulate water through the tubes. A pipe 24 is connected tothe drum 12 below the water line and leads to the inlet of thepump 22.The discharge of the pump is connected to the inlet header 19 of thewater wall. The outlet header 20 is connected by means of a pipe 26 withthe steam space of the drum 12. With this construction the pump 22 drawswater from the drum 12 through pipe 24 and delivers it under pressure toinlet header 19 and tubes 18. Thesteam which is formed in the tubes,together with any unevaporated water, passes back to the drum 12 throughheader 20 and pipe 26.

In order to insure a sufiicient pressure drop between the inlet headerand the tubes and thus obtain proper distribution of the water among theseveral tubes and prevent the steam formed in the tubes from flowingback into the inlet header, it is necessary to provide means, such asorifices, for restricting the cross sectional area available for flow atthe entrance end of each tube. The present invention is concerned withthe construction of these orifices and with means for maintaining themin proper operating condition and for preventing the operation frombeing affected by the presence of foreign material in the water. Y

In the preferred embodiment illustrated the header 19 is provided with acylindrical opening 2'7 for each tube 18, and each of these openings hasan annular groove 28 therein. The tubes are rolled into the openings 2'7and the metal is expanded into the groove 28 in a well known manner byinserting an expanding tool through a second opening 30 provided in thewall of the header directly opposite each tube. This opening 30 ispreferably screw threaded and closed by a suitable plug 31. An annulargasket 32 is placed beneath a shoulder 33 on each plug and serves toprevent leakage of the water from the header.

Atthe entrance end of each tube 18 I provide a hollow cylindrical sleeve35 having an external diameter substantially equal to the internaldiameter of the rolled portion of the tube. This sleeve is inserted intothe tube coaxially therewith and fits tightly enough to prevent leakagebetween these parts. In some cases it may be dewhich fits tightly in theinterior of the sleeve 35. This construction is preferable to anintegral one, since it permits the sleeve 35 to be made from commercialtubing and avoids considerable machining. The face of the member 39surrounding the entrance end of the orifice 37 is beveled as shown at 40so as to slope toward the orifice. This avoids sharp internal corners inwhich accretions of scale might form. The member 39 may be held in thesleeve 35 in various ways, but I prefer to contract the diameter of thesleeve slightly at each side of the member by. rolling circumferentialgrooves 41 in the external surface of the sleeve. This constructionprovides an individual screened nozzle insertable as a unit in theentrance end of the tube for supplying water thereto.

In order to prevent the entrance of foreign material into the interiorof the sleeve through the open end thereof, I provide means for at leastpartially closing this end. This I preferably accomplish by providing acylindrical member or rod 43 supported by the plug 31 and extendingcoaxially therewith into the sleeve 35. This rod 43 is preferablyslightly smaller in diameter than the interior of the sleeve, forreasons which will hereinafter appear, but this difference in diameveris, however, less than the diameter of the orifice 37, so that eventhough the parts should become out. of alignment and the rod shouldcontact with the interior of the sleeve at one side, nevertheless thespace between these parts on the opposite side would be insufiicient topermit the passage of foreign particleslarge enough to obstruct theorifice.

The wall of the sleeve 35 is provided with a plurality of openings orperforations 44 therethrough, each preferably circular in shape'and offoreign particles which might cause plugging thereof.

Such foreign particles, however, are likely to obstruct the openings inthe screen after a considerable period of operation, and there is also apossibility of chemical deposits from the water occurring in theinterior of the sleeve 35. I therefore provide for thoroughly cleaningthe orifice and screen without interfering. with the operation of thefurnace, and I obtain this result by reversing the direction of flowthrough these parts. For this purpose I provide a blow off pipe 50leading from the inlet header 19 and having a valve 51 therein, and Ialso provide means, such as a valve 52 at the discharge of the pump 22,for cutting off the supply of water from the boiler 12 to the header 19during the cleaning periods. By closing valve 52 and opening valve 51,the operator can cause steam from the drum 12 to flow under full boilerpressure through pipe 26, header 20, and tubes 18, through the orificesand screens in 'a reverse direction, and out through blow off pipe 50 toa suitable place of deposit. This steam will not only flow outwardlythrough the openings 44 in the screen, but it will also flow along theinterior surface of the screen and out through the annular space betweenthe sleeve 35 and the rod 43. It is thus possible to blow out throughthis annular space flakes of scale or chemical deposits which may haveformed inside the screen and which cannot pass through force the sleeve35 out of the tube 18 when the copending application for Letters PatentSe'rial flow is reversed for cleaning purposes. In order to prevent thisfrom happening, I provide a pin 55 extending transversely of the rod 43and closely adjacent to the end of the sleeve. The pin 55 may be made adrive fit in an opening in the rod, and serves to retain the sleeve inits proper position.

The steam flowing along the tubes 18 toward the orifices may pick upscale or other foreign material and force it into the orifices, therebybringing about the very difiiculties' which the screen 35 is intended toprevent. I therefore provide a second screen 56 to protect each orificefrom this possibility.- Each screen 56 is shaped as a fiat thin circulardisk having circular openings 58 therethrough slightly smaller indiameter than the orifice 37. The disk 56 is preferably of the samediameter as the orifice plug 39 and fits closely against the dischargeside thereof within the sleeve 35. These parts are all held in anassembled relationship by the rolling of the grooves 41. The orificeplug is shown in Fig. 2 as provided with a beveled or countersunk faceon its discharge side similar to the beveled face 40 on its inlet side,so that the screen 56 is spaced from the orifice and the screen openingsare unobstructed by the plug. The parts 35, 39 and 56 are preferablymade of some non-corrosive material, such as Monel metal. l

The operation of the inventionwill be apparent from the abovedisclosure. The pump 22 delivers water to the inlet header 19 at apressure in excess of the boiler pressure, and this water is distributedto the tubes by the orifices 37, the steam and any excess water flowingtothe boiler through pipe 26. The screens 35 prevent any clogging of theorifices by foreignmaterial in the water, and any such material whichdoes accumulate on the outside of the screens, as well as any scalewhich may form inside thescreens, may be easily removed during theoperation of the boiler by manipulating the valves 51 and 52 to reversethe direction of fiow. The construction is simple and inexpensive tomanufacture and install, and thoroughly reliable in operation.

This application is a continuation in part of my No. 140,665, filedOctober 9, 1926 Having. thus described my invention, what I claim as newand desire to secure by Letters Patent is: l v

'1. A heat exchange apparatus comprising a plurality of tubes, means fordelivering fluid into one end of each tube and causing it to flowtherethrough in ,heat exchanging contact therewith, means restrictingthe cross sectional area at the entrance end of each tube for limitingthe flow of the fiuid into the tube, and means for reversing thedirection of fiow of the fluid being heated arranged in such relation tosaid restricting means that said reverse flow of the fluid within theheat exchanger is distributed by said restricting means so thatsaid'reverse flow is caused simultaneously through all said restrictingmeans whereby foreign material is simultaneously removed therefrom. 1

2. Steam generator comprising a plurality of stea'n generating tubeseach having one of its ends connected to a header, means to supply waterunder pressure to said header for delivery into the tubes and flowtherethrough, a receptacle for steam under pressure, connections betweenthe other ends of said tubes and the steam receptacle normally todeliver thereto the steam generated in the tubes, means forming arestricting orifice at the water inlet end of each tube, a blow-off pipeconnected to the header, and valve means for reducing the pressure ofthe water in the header and opening the blow-off pipe, the arrangementof said valve means and said blow-oil relative to the header and to theorifices being such that steam from the receptacle is distributed bysaid orifices so as to be caused to flow along each tube and througheach orifice simultaneously in areverse direction and to create areverse pressure drop through the orifices, said orifices acting tomaintain within the tube a pressure not substantially diiferent fromthat within the receptacle, said reverse fiow and pressure drop thusacting to remove accumulations of foreign material in the orifices.

3. A heat exchange apparatus comprising a tube, means to supply liquidto one end thereof, a hollow cylindrical sleeve fitted endwise to saidend of the tube, and means adjacent the end of the sleeve which isfitted to the tube and formed to provide a restricting orifice insidethe sleeve through which-the liquid entering the tube must the inlet endof each tube, a hollow cylindrical.

sleeve mounted adjacent to each orifice and coaxial with thecorresponding tube, said sleeve having openings in its walls, and acylindrical member mounted within the sleeve, said cylindrical memberbeing smaller in diameter than the interior of the sleeve so as to forman annular passage between the member and the sleeve, and meanstoreverse the direction of flow through the orifice and the annularpassage while the generator is in operation.

5. A steam generator as recited in claim 4 in which each cylindricalmember is supported on a plug which is mounted in an opening in the wallof the header directly opposite to the inlet end of the tube.

6. A steam generator as, recited in claim 4 in which the end of thecylindrical member toward the tube is shaped as a conical point to guideforeign material into the annular passage when the flow is reversed. 7.A steam generator comprising an inlet header, means to supply waterunder pressure to the header, a. plurality of steam generating tubeshaving their inlet ends connected to the header,

a thin walled hollow cylindrical sleeve inserted in f the inlet end ofeach tube, a cylindrical body fitted tightly in the inside of the sleeveand having a circular fiow restricting orifice therein, the sleeve beingprovided with circular openings in its walls anterior tothe orifice andsmaller in diameter than the orifice, a fiat circular disk mountedwithin the sleeve adjacent to the discharge side of the cylindrical bodyand having a plurality of circular openings therethrough each smaller indiameter than the orifice, the sleeve having a circumferential grooverolled in its external surface anterior to the cylindrical body and asimilar groove posterior to the disk to hold these parts in position,and means to reverse the direction of flow through the orifices whilethe generator is in operation.

8. A steam generator comprising an inlet header, means to supply waterunder pressure to the header, a plurality of steam generating tubeshaving their inlet ends connected to the header, means forming a fiowrestricting orifice at the entrance end of each tube, a separatecylindrical screen at the entrance side of each orifice, a plug mountedin an opening in the wall of the header opposite to the inlet end ofeach tube, and means supported by each plug for holding thecorresponding screen in its proper position.

9. As an article of manufacture, a fluid supply nozzle for use with atube of a heat exchange apparatus comprising a thin walled hollowcylindrical sleeve formed at one end thereof so as to be fitted tightlyto the fluid inlet end of the tube, and a cylindrical body fittedtightly in the inside of the sleeve, said body having an orifice openingtherein communicating from inside the sleeve to the tube when the sleeveis fitted to the tube, said sleeve being provided with openings in itswalls anterior to the orifice relative to the flow of fluid therethroughand being so constructed and arranged that fluid flowing into the tubethrough the orifice for the most part must pass through said openings insaid walls, said openings having a diametral dimension less than thediametral dimension of the orifice.

10. A nozzle as recited in claim 9 in which the face of the cylindricalbody is beveled on the entrance side of the orifice.

11. As an article of manufacture, a fluid supply nozzle for use with atube in a heat exchange perforated screen carried bythe member andmounted at that side of the orifice which is outside the hollow space ofthe member.

12. As an article of manufacture, a fluid supply nozzle for use with atube of a heat exchange apparatus comprising a hollowsleeve of a form tobe fitted to the inlet end of the tube, a body fitted tightly in theinside of the sleeve and having an orifice therein communicating fromthe hollow space of thesleeve to the tube when the sleeve is fittedthereto, said sleeve being provided with openings in its walls anteriorto the orifice relative to the flow of fluid therethrough, and a flatperforated screen mounted .at the discharge side of the orifice, thedischarge face of said body being beveled.

13. As an article of manufacture, a nozzle for a heat exchange apparatushaving a heat exchanging tube comprising a hollow cylindrical sleeve ofaform to be fitted to the tube at the fluid supply end of the tube, anda cylindrical body fitting within said sleeve and having an orifice forlimiting the flow of fluid into the tube, said sleeve being constructedat an end thereof remote from said cylindrical body to provide at most arevapor generating tubes, means for supplying to said tubes at one endof each tube the liquid to be vaporized in quantity sufficient for theevaporation in said tubes, means connected to the other ends of thetubes for receiving the fluids discharged therefrom, means at the inletend of each tube for restricting the flow of the liquid into each tubewhile permitting its passage into the tube in quantity suflicient forthe evaporation in said tube, and means for causing fluid from saidfluid receiving means to flow by way of said tubes reversely throughsaid flow restricting means to removetherefrom foreign material, saidmeans for reversing the flow being so arranged in relation to saidrestricting means that said restricting means act to limit the flow fromsaid receiving means reversely through each tube and to distribute saidreverse flow so that said reverse flow is produced simultaneouslythrough all said restricting means.

15. A steam generator comprising a plurality of steam generating tubes,means for positively delivering to one end of each of said tubes underpressure greater than that existing in the tubes water in quantitygreater than can be evaporated in passage of the water through thetubes, means at the water inlet end of each tube providing an orificefor maintaining a pressure drop while limiting the water entering thetube to a quantity insufiicient to fill the internal cross sectionalarea of said tube, means connected to the discharge end of the tubes forcollecting the steam and water discharged from the tubes, and means forcausing the steam and any water carried'therewith from said collectingmeans to flow in reverse direction through the tubes and arranged inrelation to said orifices so that said reverse fiow is distributed bysaid orifices simultaneously to flow reversely therethrough under areverse pressure drop and to be exhausted from the generator on thewater delivery side of said orifices to remove foreign materialtherefrom.

-16. As an article of manufacture, a fluid supply nozzle for use witha'tube of a heat exchange apparatus comprising a hollow sleeve of a format one end thereof to fit to the fluid inlet end of the tube, saidsleeve being constructed adjacent said end thereof so as to close saidhollow sleeve but to provide an orifice opening from the hollow spacewithin the sleeve to the tube when the sleeve is fitted thereto, saidsleeve being constructed, at the other end thereof to provide restrictedif any opening and being provided with openings in the walls enclosingthe hollow space communicating from outside the sleeve to the hollowspace within the sleeve for passage of fluid to said space, said.openings being of restricted size in relation to the size of saidorifice opening but of sufiicient number to provide for the flow of thefluid to the orifice for passage therethrough into the tube.

17. As an article of manufacture for use with a tube of a heat exchangeapparatus, the combination with a fluid supply nozzle in the form of ahollow sleeve having screening openings in the 18. A heat exchangeapparatus comprising a.

plurality of tubes arranged for heating a fluid under a selectedpressure, means normally acting to deliver fluid into one end of eachtube and to cause it to flow therethru in heat exchanging contacttherewith, means restricting the cross sectional area at, the entranceend of each tube for limiting the fiow of the fluid into the tube andproducing a pressure drop at said end thereof, and means for stoppingthe normal flow of said fluid and concomitantly reversing the directionof fiow and of the pressure drop thru the restricting means of the fluidbeing heated, said means being arranged in such relation to saidrestricting means that said reverse flow of the fluid within the heatexchanger is distributed by said restricting means so that said reverseflow is caused simultaneously through all said restricting means wherebyforeign material is simultaneously removed therefrom.

19. A vapor generator comprising a plurality of vapor generating tubesconnected in a closed circuit for circulation of the liquid to beevaporated, means in said circuit for causing the liquid to flowtherethru and to be delivered to one end of each tube, means at saidinlet end of each tube for restricting the flow of the liquid into thetube and providing a pressure drop in said liquid for causing thegenerated vapor and any liquid in excess of that evaporated to: bedischarged from the opposite end of the tube, means for returning to theliquid delivery means any excess liquid so discharged from the tube,means for stopping the creation of the pressure upon said restrictingmeans of the liquid being delivered to the tube, and means for reducingsaid pressure below the pressure of the vapor and of any liquid withinthe tube and so arranged in relation to said restricting means assimultaneously to cause a reverse pressure upon each restricting meansand a distributed reverse flow of the vapor and any liquid within thetube thru all said restricting means simultaneously to remove foreignmaterial therefrom.

20. In a steam generator having a plurality of steam generating tubesconnected in a closed water circuit having therein a pump for deliveryof the water thru said circuit and said tubes, the combination withmeans providing an orifice at the water inlet end of each tube forlimiting the flow of water into said tube and for creating a pressuredrop thru the orifice of means for reducing the pressure upon the waterdelivery side of .said orifices below the pressure of steam and waterwithin the tubes, said means being so arranged in relation to saidorifices as simultaneously to reduce said pressure upon all the orificeswhile maintaining substantially normal pressure in said tubes and in theremainder of the circuit to cause steam and any water carried therewithsimultaneously to flow reversely through all the orifices in amountcapable of removing foreign material therefrom.

WALTER DOUGLAS LA MONT.

